Frictional device



July 15, 1941. v 5, Y wELLMAN 2,249,282

FRICTIONAL DEVICE Original Filed May 26, 1939 INVENTOR" BYSAMUEL A- WELLMAN ATTORNEY Patented July 15, 1941 I UNITED-4 STATES PATENT I OFFICE FRICTIONAL DEVICI'E bamnel K. Wellman, Cleveland Heights, Ohio, as-

signor to The S. K. Wellman Company, Oleve- 1 land, Qhlo, a corporation of Ohio Original application May 26, 1939,;Serlal No.

275,837. Divided and this application January 27, 1941, Serial No. 376,098

Claims.

This invention relates to frictionaldevices and more particularly to means for improving the operating characteristics of clutches and brakes More specifically it relates to a cushioned frictional facing structure adapted for use in a device wherein the frictional surfaces are brought into' engagement while wholly or partially immersed in a liquid, and to the use of cushioning means in cooperation with the facing structure.

It is the primary object of the invention to provide means for reducing or eliminating chattering and grabbing in friction clutches and for overcoming non-uniform action of brakes.

The unit is secured at one end to the brake band 2 by means of rivets B, 8, or by. any-other suitable fastening means. Near the opposite end of v the unit there-is provided a recess 9, having a cushion element, I ll, positioned therein for the be understood that the facings 3, 3 arethus pre- In order to explain my invention and its advantages, reference is made to the accompanying drawing, in which one embodiment of the invention is shown.

Fig. 1 is an elevational view ofa brake band and drum assembly showing a brake 'band having a plurality of friction facing units secured to its inner surface.

Fig. 2 is an enlarged plan view of one of the facing umts as taken along the line 2, 2 of Fig. 1.

Fig. 3 is a sectional view taken alongY-the line 3, 3 of Fig. 2..

Fig. 4 is an enlarged plan view of aldisc -spring adapted for use in the facings of Fig. 1.

Fig. 5 is a sectional-view of the spring of Fig. 4 taken along the line 5, 5 thereof. j

Fig. 6 is a sectional view of the spring of Fig. i

taken along the line a, 8 thereof.

Referring now to Figure 1 it will be seen that the brake assembly consists of a brake drum. i

. and a brake band 2, the latter having a plurality of facing units 3, 3 secured to its innersurface. The particular feature in this structure is the cantilever type cushion mounting which is provented from bearing over their entire surface against the drum 6 until suiiicient pressure has .been applied to them to overcome the strength of the cushioning springs.

The-spring I0 of Fig. 3 is shown greatly enlarged in Figs. 4, 5 and 6. The spring consists of a disc I I of spring'sheet metal which is curved cylindrically as shown in Figs. 5 and 6 about an axis extending parallel to a diameter-of the disc so as to form a portion of a cylinder. The curvature of the member is of course immaterial to its 1 operation, and may be either single or compound.

vided for at least one end portion of each of the facing units. The mounting will be better'understood through reference to Figures 2 and 3, in

which it will'be seen that each unit is rigidly secured. at one end-to the brake band, while the other end is flexibly supported on a cushion element placed between the unit and the band. A composite facing element has been illustrated here, but it will, of course, be understood that homogeneous types of facing materials could be used as well. The composite units consist of a sintered powder-metal friction surface i, bonded' to a metallic backing member 5. The major portion of this friction surface may be divided into smaller areas by means of the intersecting Furthermore, various other shapes of springs may be used as illustrated in United States application, Serial No. 275,837, from which this subject matter was divided. In the spring shown in Fig. 4 a central opening I2 is provided, and situated.

around the periphery of this opening and extending outwardly from the convex side of the spring, are projections l3, It the surfaces of which form wall portions of a cylinder. These projections or tangs are adapted to fit tightly into a hole M positioned centrally in the recess 9. It will therefore be seen that the tangs are used to center the spring in the recess and to holdit securely in place prior to and during assembly, and during use.

While the mounting arrangement. shown in Figures 1, 2 and 3 is suitable for usewherever a cushion action is desired to improve the smoothness of operation of a frictional device, the cantilever structure which is illustrated is particularly desirable where a friction surface runs in liquid. For example, some types of brakes are constructed so as to be wholly or partially immersed in' an oil bath, one usual purpose of which is to facilitate cooling of the brake members. Under such conditions the friction characteristics of the facing material are prevented from exerting thei1 full. influence at thefirst moment of contact or .foran interval of time thereafter until the 0111 filmseparating the facing from the brake drun has been broken down or removed. The oil film c 2 v between the members produces If-016Gb that the brake seemingly fails to have any braking action for an interval of time after it is applied. It may then suddenly take effect so violever cushion structure which is shown here .has

been found to be very helpfulin overcoming this difficulty. The unscored portion 1 of the facing is provided for use in this connection. Assuming that a brake drum I is rotating in a counter.- clockwise direction with respect to brake band 2, it will be-seen that the cushioned and unscored end of each of the friction unitswill first contact the rotating ,drum; with theiiresult that portion 1 will be caused to bear under low pressure upon the drum and act as a scrapenwhich will remove the excess oil and tend to reduce the thickness of the oil film remaining upon the surface of drum I. Now as the brake pressure is increased, the cushion ill will be compressed into its recess with the result that more frictional material will that said second friction member is first engaged by said yieldingly mounted end of said first member, said first friction member being so arranged that said yieldingly mounted end is the leading end and is effective in removing excess liquid from the surface of said second member.

' 2. In a friction device having friction surfaces which operate in a liquid, the combination of: a support having a first generally-elongated, relatively thin friction memberdisposed flatwise thereon and secured at one of its ends to said support, its opposite end being yieldingly mountfriction member having desired frictional char- J acteristics relative to the exposed face of said first member, and the relative motion between he brought into contact with the drum. This increased area will then tend to reduce the thicktype of difficulty occurs when it is operated in a liquid.

While the invention has been described in connection with preferred embodiments wherein the advantages are most readily apparent, it should be understood that the principles may be applied to many uses not mentioned specifically herein. Furthermore, the illustrations represent mere exemplary structures, many modifications of whichwill occur to those skilled in the art. It accordingly is desired that the invention be restricted in scope only by the following claims.

This is a division of my application Serial Number 275,837, filed May26, i939.

ness of the oil film even further so that as this said faces being such that said second friction member being so arranged that said yieldingly mounted end is effective in removing excess liquid from the surface ofsaid second member.

3. The combination as claimed in claim 2 wherein the engageable surface of said first friction member is traversed with grooves which extend partway thro'ugh its thickness and are disposed within an area of said face extending from the secured end of said member to an intermediate position and wherein the area of said face which extends from said intermediate position to the unsecured end of the member is free of grooves. I

4. In a frictional braking device adapted to operate in a liquid, the combination of:- a brake drum adapted for rotation about its axis; a bandlike support having a plurality of elongated plate- Having now fully explained my invention, by

what I claim is:

1. 'In a frictional device having'engageable friction surfaces which operate in a liquid, the

combination of: a support having a first generally-elongated, relatively thin friction memberdisposed atwise thereon and secured within a portion erect to said support, one end of said member being yieldingly mounted for movement like friction segments of reinforced slntered metal disposed flatwise thereon in concentric relation to the per heral surface of said drum for wiping.

engagement with said peripheral surface, each of said segments having an end edge which is adapted to remove excess liquid from said surface toward and away from said support while being Menu-face, said element having an edge which is held away therefrom: a second friction member having a face thereof disposed for relative motion with respect to said first friction .member when broughtinto face to face contact adapted to remove excess liquid from said surface when the direction of rotation of the member makes said edge the leading edge of the element; and means for bringing said leading edge into therewith, the face of said second friction mem- 05 wiping engagement with said surface in advance her having desired frictional characteristics relativeto the exposed face of said first member, and the relative motion between said faces being such of other portions of the element.

SAMUEL K. WELLMAN'. 

